Thin film transistor and manufacturing method thereof, array substrate and manufacturing method thereof, display device

1. A manufacturing method of a thin film transistor, comprising: forming a gate electrode, a gate insulating layer, a semiconductor active layer and an ohmic contact layer on a substrate; exposing and developing a photoresist on the substrate from a back side of the substrate by taking the gate electrode as a mask plate, wherein a remaining portion of the photoresist after exposing and developing covers the gate electrode; forming a source-drain metal thin film on the substrate; stripping off the remaining portion of the photoresist and the source-drain metal thin film on the remaining portion of the photoresist to form a gap between a source electrode and a drain electrode of the thin film transistor; etching the ohmic contact layer in the gap; and etching the source-drain metal thin film to form the source electrode and the drain electrode.

2. A manufacturing method of an array substrate, comprising: forming a gate electrode, a gate line, a gate insulating layer, a semiconductor active layer, an ohmic contact layer and a transparent conductive electrode on a substrate; exposing and developing a photoresist on the substrate from a back side of the substrate by taking the gate electrode as a mask plate, wherein a remaining portion of the photoresist after exposing and developing covers the gate electrode; forming a source-drain metal thin film on the substrate; stripping off the remaining portion of the photoresist on the ohmic contact layer and the source-drain metal thin film on the remaining portion of the photoresist, to form a gap between a source electrode and a drain electrode of a TFT; etching the ohmic contact layer in the gap; and forming the source electrode, the drain electrode, a data line and a passivation layer on the substrate.

3. The method according to claim 2 , wherein the step of forming the gate electrode, the gate line, the gate insulating layer, the semiconductor active layer, the ohmic contact layer and the transparent conductive electrode on the substrate comprises: sequentially forming a transparent conductive thin film and a gate metal thin film on the substrate; coating a layer of photoresist on the substrate, exposing and developing the photoresist through a dual-tone mask plate so as to form a photoresist-completely-reserved region, a photoresist-partially-reserved region and a photoresist-completely-removed region, wherein the photoresist-completely-reserved region corresponds to a region where the gate electrode and the gate line are to be formed, the photoresist-partially-reserved region corresponds to a region where the transparent conductive electrode is to be formed, and a remaining region is the photoresist-completely-removed region; etching the gate metal thin film and the transparent conductive thin film of the photoresist-completely-removed region through an etching process, to form the gate electrode and the gate line; removing the photoresist of the photoresist-partially-reserved region by an ashing process; etching the gate metal thin film of the photoresist-partially-reserved region through an etching process; stripping off the photoresist of the photoresist-completely-reserved region; sequentially forming a gate insulating layer thin film, a semiconductor active layer thin film and an ohmic contact layer thin film on the substrate; coating a layer of photoresist on the substrate, exposing and developing the photoresist through a dual-tone mask plate so as to form a photoresist-completely-reserved region, a photoresist-partially-reserved region and a photoresist-completely-removed region, wherein the photoresist-completely-reserved region corresponds to a region where the active layer of the TFT is to be formed, the photoresist-partially-reserved region corresponds to a region where the gate line is formed, and a remaining region is the photoresist-completely-removed region; etching the ohmic contact layer thin film, the semiconductor active layer thin film and the gate insulating layer thin film of the photoresist-completely-removed region through an etching process, to form the semiconductor active layer and the ohmic contact layer; removing the photoresist of the photoresist-partially-reserved region by an ashing process; etching the ohmic contact layer thin film and the semiconductor active layer thin film of the photoresist-partially-reserved region through an etching process; and reserving a remaining portion of photoresist of the photoresist-completely-reserved region.

4. The method according to claim 2 , wherein the step of forming the source electrode, the drain electrode, the data line and the passivation layer on the substrate comprises: forming a passivation layer thin film on the substrate; coating a layer of photoresist on the substrate, exposing and developing the photoresist through the dual-tone mask plate so as to form a photoresist-completely-reserved region, a photoresist-partially-reserved region and a photoresist-completely-removed region, wherein the photoresist-completely-reserved region corresponds to a region where the active layer of the TFT is formed, the photoresist-partially-reserved region corresponds to a region where the data line is formed, and a remaining region is the photoresist-completely-removed region; etching the passivation layer thin film of the photoresist-completely-removed region through an etching process; etching the source-drain metal thin film of the photoresist-completely-removed region through an etching process; removing the photoresist of the photoresist-partially-reserved region by an aching process; etching the passivation layer thin film of the photoresist-partially-reserved region through an etching process; and stripping off a remaining portion of the photoresist of the photoresist-completely-reserved region.

5. The method according to claim 2 , wherein the array substrate further comprises a transparent conductive layer provided on the substrate; and the transparent conductive layer is provided below the gate electrode of the TFT, and the transparent conductive electrode is provided in a same layer as the transparent conductive layer.

6. The method according to claim 2 , wherein the transparent conductive electrode is served as a pixel electrode and is electrically connected to the drain electrode of the TFT.